Glutamine supports cell survival, growth and proliferation through metabolic and non-metabolic mechanisms. In actively proliferating cells, the metabolism of glutamine to lactate, also referred to as “glutaminolysis” is a major source of energy in the form of NADPH. The first step in glutaminolysis is the deamination of glutamine to form glutamate and ammonia, which is catalyzed by the glutaminase enzyme (GLS). Thus, deamination via glutaminase is a control point for glutamine metabolism.
Ever since Warburg's observation that ascites tumor cells exhibited high rates of glucose consumption and lactate secretion in the presence of oxygen (Warburg, 1956), researchers have been exploring how cancer cells utilize metabolic pathways to be able to continue actively proliferating. Several reports have demonstrated how glutamine metabolism supports macromolecular synthesis necessary for cells to replicate (Curthoys, 1995; DeBardinis, 2008).
Thus, glutaminase has been theorized to be a potential therapeutic target for the treatment of diseases characterized by actively proliferating cells, such as cancer. The lack of suitable glutaminase inhibitors has made validation of this target impossible until the recent creation of compounds that are specific and capable of being formulated for in vivo use (U.S. Pat. No. 8,604,016). As glutaminase inhibitors enter the clinical arena, methods are needed to identify patients that would best benefit from treatment with these compounds.